1-(4-Amino-6,7-dimethoxy-2-quinazolinyl)-4-tetrahydrofuroylpiperazine hydrochloride is known by the common name "terazosin" and is the subject of U.S. Pat. No. 4,026,894.
Pharmaceutical compositions comprising terazosin or a pharmaceutically acceptable salt: and the use of such compositions for the treatment of hypertension are disclosed and claimed in U.S. Pat. No. 4,112,097.
The dihydrate of terazosin, its preparation, pharmaceutical compositions containing the dihydrate, and their use for the treatment of hypertension are disclosed and claimed in U.S. Pat. No. 4,251,532.
U.S. Pat. No. 5,212,176 discloses and claims the R(+)-enantiomer of terazosin hydrochloride dihydrate, pharmaceutical compositions containing the R(+)-enantiomer, and their use in the treatment of hypertension, benign prostatic hyperplasia, hyperinsulinemia, and congestive heart failure.
The Form II crystalline modification of anhydrous terazosin hydrochloride is the subject of U.S. Pat. No. 5,294,615 and processes for its preparation are disclosed in the continuation-in-part, U.S. Pat. No. 5,362,730.
The Form III crystalline modification of anhydrous terazosin hydrochloride and the crystalline methanolate of terazosin hydrochloride are the subjects of U.S. Pat. No. 5,412,095.